I melted my crayons on a flat paper or canvas, placed in a warm oven. (150 degrees) When soft and runny I removed and encouraged the wax to run by tilting.
I found white was key in making the pattern come alive. Unfortunately some packages of crayons don't include any white . White Candles melt into a dull yellowy white so didn't make the best substitute.
I had a wonderful day experimenting with crayons, canvas, a warm oven and my hair blower. All Thanks to pinterest.com/! I placed my crayons on a canvas which was at a slight angle in a warm oven. As the crayons started to melt I took them out of the oven for a few seconds of directional encouragement with my hair blower. I was very sure that I wouldn't get wax on my blower so I didn't use an old one. . .well it took me some time to remove the wax!
The grade three class had fun pounding out these images onto napkins. First arrange fresh ferns on a smooth, clean, hard surface. We used 12"X12" pieces of wood. Next place the napkin over the design, tape it in place to keep it from moving. Each student had a fist sized rock which they used to pound out the design, transfering the chlorophyl from the plant into the fabric. A very noisy classroom! My grandsons made these a year ago and with many washings have faded only slightly. [the napkins not my grandsons : ) ]